High vacuum electric furnace



April 29, 1969 H. w. WESTEREN.

HIGH VACUUM ELECTRIC FURTTACE Sheet of 5 IWENTOR HERBERT W. WESTEREN BY M FM 4 ATTORNEYS Filed Dec. 31, 1964 April 1969 H. w. WESTEREN 3,441,452

HIGH VACUUM ELECTRIC FURNACE Filed Dec. 31, 1964 Sheet 2 of 5 FIG.2

INVENTOR. HERBERT W. WESTEREN )ZLQVAM ATTORNEYS April 29, 1969 H. w. WESTEREN 3,

HIGH VACUUM ELECTRIC FURNACE I Filed Dec. 31. 1964 Sheet 3 of 5 INVENTOR. HERBERT w. WESTEREN ATTORNEYS April 1969 H. w. WESTEREN 3,441,452

HIGH VACUUM ELECTRIC FURNACE Filed Dec. 31, 1964 Sheet 4 of 5 /66 92 Q? 6o 1 =4 5 FIG. 9

INVENTOR.

HERBERT W. WESTEREN BY M 7M ATTORNEYS April 29, 1969 H. w. WESTEREN HIGH VACUUM ELECTRIC FURNACE Sheet 5 Filed Dec. 51. 1964 FIG 5 o w WW5 7 a 2 w? a g T l w T w 9 5 8 w 5 o INVENTOR, HERBERT W. WESTEREN ATTORNEYS United States Patent 3,441,452 HIGH VACUUM ELECTRIC FURNACE Herbert W. Westeren, Harrington, R.I., assignor to C. I. Hayes, Inc., Cranston, R.I., a corporation of Rhode Island Filed Dec. 31, 1964, Ser. No. 422,617 Int. Cl. C21d 1/74, 1/34 US. Cl. 148-143 17 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a high vacuum electric furnace. More particularly the present invention relates to an electric furnace for heat treating metallic articles therein, the interior of the furnace being maintained under vacuum during the heat treatment cycle, and the articles that are heat treated being transferred from the heating zone in the furnace to a quenching zone Without removal of the articles from the area in the furnace that is maintained under vacuum.

In the heat treatment of metallic articles such as carbon and stainless steels or the like, it is critical in certain conditions of use thereof that the surfaces thereof be maintained free of contamination that results from oxidation and/or decarbnrization. The technique employed in the present invention in providing for an exceptionally clean surface of the articles being heat treated, is to maintain the interior of the heat treatment furnace under vacuum while the articles are being heat treated therein. By maintaining the furnace under vacuum the remaining gases therein are neither oxidizing or decar'ourizing and surface changes in the articles being heat treated are prevented.

The furnace of the present invention is also unique in that the articles that are heat treated therein are rapidly quenched in an oil bath without removal of the articles from the area of the furnace under vacuum. Thus after the articles are placed within the furnace, the interior thereof is evacuated to a predetermined vacuum pressure, after which the articles are moved into a heating zone for the heat treatment thereof. After completion of the heat treatment cycle, the articles are removed from the heating zone and are then transferred to a quenching area that communicates with the evacuated furnace interior. Since the articles are removed from the heating zone and transferred to the quenching zone in a matter of a few seconds, rapid quenching thereof occurs which is essential for protecting the surfaces of the heat treated articles. By rapidly quenching the articles and without removing them from the evacuated area, oxidation and/ or decarburization is prevented and the resulting heat treated articles are provided with a highly clean and bright appearing surface.

Since the operation of the furnace of the present invention is dependent upon the establishment of a high vacuum therein, movement of the articles to be heat treated within the furnace is carried out by a remotely controlled device after the loading of the articles within the furnace.

3,441,452 Patented Apr. 29, 1969 The articles are placed in the furnace on a load platform of a support member and support member is then moved by the remote control device in a longitudinal direction to a heating zone. Movement of the load support member is facilitated by securing the support member to a slide plate that is adapted to be received within a track assembly. The track assembly is defined by two aligned but disconnected longitudinally extending track sections, one of the track sections being located at the load station and being connected to a ring cage assembly that is mounted for rotary movement. The other of the track sections is aligned with and adjacent to the first track section but is disconnected therefrom, extending beneath the heating zone of the furnace. The load support member is thus transferred directly from the first track section onto the second track section and into the heating zone, for heat treatment of the articles carried thereon. After the articles have been heat treated for the required period of time the load support member is withdrawn from the heating zone and onto the first track section. Since the first track section is adapted for movement with the ring cage assembly, the remote control device that is interconnected to the ring cage assembly is actuated whereby the ring cage assembly and the load support member are rotated in an arcuate path. This movement dumps the heat treated articles from the load support member into a quench tank that is located directly beneath the first track section. The interior of the quench tank in which a quench liquid is contained is maintained in direct communication with the interior of the furnace, so that when the articles are transferred to the quench tank they are done so without the removal thereof from the evacuated area in the furnace housing. Quenching of the heat treated articles is thus carried out by a rapid transfer of the articles from the support member to the quench tank, thus ensur ing that rapid quenching of the articles is achieved. Since the articles are continuously exposed to the vacuum prior to introduction into the quenching oil contained in the quench tank, surface contamination of the articles is prevented and an unusually clean and bright surface of the articles results.

Accordingly, it is an object of the present invention to provide a high vacuum furnace for heat treating and quenching work pieces in such a manner as to prevent contamination of the surfaces thereof.

Another object of the invention is to provide a high vacuum electric furnace in which articles to be heat treated are moved therein by remotely controlled means for transfer to and from a heating zone and for introduction into a quenching zone.

Still another object is to provide a high vacuum furnace in which a load platform located within the housing of the furnace is moved in a longitudinal direction to and from a heating zone and is further moved in an arcuate path after the heat treatment cycle for transfer thereof to a quenching zone.

Still another object is to provide a track assembly that is used in a high vacuum furnace for transferring a load support member to and from a heating zone and to a quenching zone, the track assembly including a pair of aligned track sections, the first of which is movable in an arcuate path for transfer of the heat treated articles to a quenching zone, and the second of which is disconnected from the first track section and fixed beneath the heating zone. 1

Still another object is to provide a high vacuum furnace having remotely controlled transfer apparatus for moving a load support member and articles carried thereby to and from a heating zone and for further moving the support member in a manner to transfer the articles to a quench tank after the heat treatment thereof.

Still another object is to provide quenching apparatus for use in a high vacuum furnace that includes a unique arrangement of bafiles for preventing any quenching medium that is vaporized from entering the interior of the furnace and that further includes means for securing a quench tank in communication with the furnace housing.

Other objects, features and advantages of the invention will become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.

In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:

FIG. 1 is a vertical sectional view with parts shown in elevation of the furnace construction embodied in the present invention;

FIG. 2 is a sectional view taken along lines 22 in FIG. 1;

FIG. 3 is a sectional view taken along lines 33 in FIG. 1;

FIG. 4 is a sectional View taken along lines 44 in FIG. 1;

FIG. 5 is a sectional view taken along lines 55 in FIG. 1;

FIG. 6 is a sectional view taken along lines 66 in FIG. 1;

FIG. 7 is a sectional view taken along lines 7-7 in FIG. 1;

FIG. 8 is a sectional view taken along lines 88 in FIG. 1; and

FIG. 9 is a sectional view taken along lines 9-9 in FIG. 4.

Referring now to the drawings and more particular to FIG. 1, the vacuum furnace embodied in the present invention is illustrated and is generally indicated at 10. Since the vacuum furnace 10 is operated at a predetermined vacuum, which under normal operating conditions may be approximately 1O' 10 mm. Hg, any suitable vacuum equipment may be connected thereto for evacuating the interior thereof as required. As illustrated in FIG. 1, the vacuum furnace 10 includes a housing generally indicated at 12 that is defined by a cylindrical section 14 to which end Walls 16 and 18 are joined. A flange is fixed to the forward end wall 16 of the cylindrical section 14 and cooperates with the end Wall 16 to seal the forward end of the housing 12. A cooling jacket 20 surrounds the major portion of the cylindrical section 14, while end cooling jackets 22 and 24 are joined to the end Walls 16 and 18 respectively. A cooling fluid such as water may be circulated in the spaced defined by the cooling jackets 20, 22 and 24 for maintaining the temperature of the housing walls at a prescribed level.

Supporting the housing 12 are spaced vertically extending supports 26 and 2 8, the vertical support 26 being located substantially at the front of the housing 12 while the vertical support 28 is located substantially at the rear of the housing 12. Interconnecting the vertical supports 26 and 28 are spaced horizontal supporting members 30' and 32, the vertical supports 26, 28 having a tapered configuration as seen in FIGS. 2 and 5 and the horizontal supports 30, 32 'being formed in channel con-figuration for connection to the vertical supports 26 and 28. Joined to the front vertical support 26 and extending forwardly with respect thereto is a support housing generally indicated at 33 and defined by an upper wall 34, a front wall 36, a bottom wall 38 and sidewalls 40. The forward housing 33 is adapted to conceal operating apparatus that is designed to remotely control the movement of a work support member mounted within the furnace housing 12, as will hereinafter be described.

Located within the housing 12 and adjacent to the rear end Wall 18 is a heating chamber generally indicated at 42 in which a heating zone is defined. As seen in FIGS. 1 and 6, the heating chamber 42 includes a substantially cylindrical casing 44 the bottom portion of which is fiattened as indicated at 46, the casing 44 having a rear end wall 48 and a forward end wall 50 joined thereto. An outer shell 52 surrounds the casing 44 and has brackets 53 joined thereto for securement to supports 54 that are, in turn, connected to the inner surface of the cylindrical section 14. As shown in FIGS. 5 and 6, the forward end wall 50 of the heating chamber 42 has a substantially square shaped opening 55 formed therein that communicates with a reduced vertically extending opening 56 that extends downwardly therefrom through the fiat bottom portion 46. Communicating with the opening 56 and formed centrally in the flat bottom wall 46 and outer shell 52 is a longitudinally extending opening 58. As will hereinafter be described, the square shaped opening 54 and the openings 56 and 58 as formed in the forward end wall 50 and the bottom wall 46 of the heating chamber 42 are adapted to provide for receiving a load support member that is moved into the interior of the heating chamber 42 during the heat treatment period.

Mounted Within the casing 44 of the heating chamber 42 is a heating unit generally indicated at 60. The heating unit includes a plurality of woven graphite flexible heating elements 62 that are interconnected at the forward end thereof to spaced arcuate segments 64 and at the rearward end thereof to an annular conducting ring 66. Opposed terminals, one of which is indicated at 68 are joined to the arcuate segments 64 and extend outwardly of the casing 44 and housing 12 for electrical communication with a source of power. Referring to FIG. 4, mounting sleeves 70 are fixed to the cylindrical section 14 of the housing 12 and provide for feed through of the terminals 68 therein. A graphite support member 72 (FIG. 1) is fixed to the ring 66 and is mounted in an electrically insulated support element 74 for supporting the heating unit 60 within the heating chamber 42. In connection with the specific construction of the heating unit 60, reference is made to co-pending application Ser. No. 262,686 filed Mar. 4, 1963.

One of the features of the furnace embodied in the present invention is that the heat treatment cycle is carried out under vacuum, that is the interior of the furnace is maintained under a predetermined vacuum throughout the heating cycle of the furnace. In order to evacuate the interior of the cylindrical section 14 and the associated portions communicating therewith, a vacuum connection indicated at 74 in FIG. 1 is provided and is adapted to be joined to a similar connection that is formed as part of a high vacuum pump. A port 76 that is formed in the rear end wall 18 communicates with the interior of the housing 12 and with the connection to the vacuum pump and provides for evacuating the housing as required. In order to provide for loading and unloading of the articles into and out of said housing, a door indicated at 73 in FIG. 4 is mounted on the cylindrical section 14 and has a view port located therein that provides visual inspection of the housing interior with the door located in locked position.

Once the articles to be heat treated are loaded into the furnace, the interior thereof is evacuated and the articles are then moved into the heating chamber 14 for the heat treatment thereof. In order to load the articles within the interior of the furnace housing 12 a support member generally indicated at 77 is provided and is defined by a platform 78 to which pedestals 80 are joined, the pedestals 80, in turn, being fixed to a slide plate 82 at the lowermost ends thereof. The platform 78 is formed with opposed tracks 84 that define a channel for receiving the flanges joined to a load basket 86 or the like in which the articles to be heat treated are carried. It is understood that the interfitting of the tracks 84 and the flanges formed on the basket 86 prevent movement of the basket with respect to the platform 78 during transfer of the work pieces located therein to a quenching zone as will hereinafter be described.

As shown in FIG. 1, the support member 77 on which the basket 86 is mounted is located in that position after the loading thereof. Since the support member 77 must be moved in a longitudinal direction from the position illustrated in full lines in FIG. 1 to the position illustrated in dotted lines within the heating chamber 42, a track assembly defined by a first track section 88 and a second track section 90 is provided. The track sections 88 and 90 extend in a longitudinal direction, the second track section 90 being a continuation of the first track section 88 but disconnected therefrom. As will be described, the first track section 88 is adapted to be moved in a rotary or arcuate path for transferring the heat treated articles in the basket 86 to a quenching zone. Thus, the track section 88 is disconnected from and is moved with respect to the track section 90. As shown in FIGS. 1 and 5, the first track section 88 is joined to circular rings 92 and 94 that are formed as part of a ring case assembly generally indicated at 96. The ring cage assembly 96 is adapted to be rotated through a prescribed arcuate path for transfer of the heat treated articles to a quenching zone and for this purpose carries the support member 77 therewith. Since the first track section 88 is fixed in the ring case assembly 96, rotary movement of the ring cage assembly 96, will carry the track section 88, and the support member 77 therewith. The construction of the ring cage assembly 96 and the operating means therefor will be described hereinafter.

As previously described the second track section 90 is fixed in position and as shown in FIG. 1 is mounted on channel supports 98 that are secured to crossbeams 100. The fixed track section 90 defines a continuation of the first track section 88 in its normal position and is adapted to transfer the support member 77 and basket 86 thereon into the heating chamber 42. The construction of the fixed track section 90 is similar to that of the first track section 88 and includes opposed channel elements that define the track. The opposed channel elements are shown more clearly in FIGS. 4 and 5.

When the support member 77 including the platform 78 and pedestals 80 together with the work basket 86 are moved into the interior of the heating chamber 42, the pedestals 80 are received within openings 56 and 58 while the platform 78 and the work basket 86 thereon pass, through the square opening 54 in the forward wall 50 of the casing 44. During the heating cycle the heat chamber 42 must be enclosed so as to provide for generation of the required heat therein. In order to seal the forward wall 50 and the flat bottom portion 46, shields 102 and 104 are provided and are joined to the pedestals 80 of the support member 77 and are adapted to be moved therewith. The lower shield 102 is relatively fiat as illustrated in FIG. 5, and is adapted to be moved into overlying relation with respect to the opening 58 formed in the flat bottom portion 46 of the casing 44. The upwardly extending shield 104, that is joined to the lower shield 102, has a configuration that generally corresponds to the configuration of the square-shaped opening 54 and the reduced opening 56 formed in the forward end wall 50 of the heating chamber 42, but is somewhat larger with respect thereto as shown in FIG. 4. Thus when the support member 77 is moved to the position shown in dotted lines in FIG. 1, the shields 102 and 104 are moved therewith into overlying relation with respect to the openings 54, 56 and the lower opening 58 so as to substantially seal the interior of the heating chamber 42.

Since the support member on which the basket 86 is mounted must be moved in a longitudinal direction after sealing of the furnace housing and the evacuation of the housing interior, a remotely controlled device is interconnected to the slide plate 82 for controlling the movement thereof and the support member 77 mounted thereon. As shown in FIGS. 1 and 8, a connecting bar 106 is fixed to the slide plate 82 and has a notch 108 formed therein adjacent to the outermost edge thereof. Extending into the notch is a pin 110 that is fixed to an elongated rod 112 adjacent to an end thereof. The notch 108 is provided in the connecting bar 106 for disconnecting the bar 106 from the elongated rod 112 when the slide plate 82 is rotated with the track section 88 by the ring cage assembly 96. This movement as described is necessary during transfer of the heat treated articles to a quenching zone and will be described in more detail hereinafter.

The elongated rod 112 extends through a series of housing elements indicated at 114, 116 and 118, these housing elements being co-extensive, and being joined by couplings 122, 124, 126 and 128 respectively. The housing elements 116, 118 and through which the elongated rod 112 extends are suitably fixed in position on the outwardly extending enclosure 33 in which the remote control devices are located, and as further seen in FIG. 1, the inner element 116 is joined to the forward end wall 16 of the housing 12, the bar 112 extending through a suitable opening formed in the wall 16 and being received within the interior of the cylindrical section 14.

In order to move the elongated bar 112 in a longitudinal direction and thereby effect longitudinal movement of the slide plate 82 and the support member 77 mounted thereon, a plurality of rack teeth 130 are formed on the upper surface of the rod 112. The rack teeth 130 engage a pinion 132 that is mounted in an enlarged portion 134 of the housing element 118 and extends through a gear housing 133. A sprocket 135 is mounted on the shaft that carries the pinion 132 and will rotate the pinion as will be described hereinafter. Fixed to supports 136 mounted on the walls 40 of the outwardly extending enclosure is a remote control device generally indicated at 145 that includes a plate 138 on which bearing housings 140 are secured. The shaft of an idler sprocket 142 is mounted for rotation in the bearing housings 140 and a chain 144 engages the idler sprocket 142 and interconnects the sprocket 142 to sprocket gear 135. A housing 143 that is mounted on the enclosure 33 encloses the pin ion 132, gear housing 133, sprocket 135 and a portion of the chain 144. Mounted for movement within an air cylinder 146 that is mounted on suitable supports that are, in turn, fixed to the walls 40 of the outwardly extending enclosure 33 is a piston rod 148 that is interconnected to the chain 144 through a coupling 150. Air under pressure is introduced into the cylinder 146 through lines 152 and 154 for controlling movement of the piston rod 148 and consequently the movement of the chain 144 and the elongated rod 112. It is seen that movement of the elongated rod 112 may be remotely controlled by controlling the operation of the remote control device 145. As the elongated rod 112 is moved in a longitudinal direction, the connecting bar 106 and slide plate 82 joined thereto are also longitudinally moved therewith. Since movement of the slide plate 82 and the support member 77 mounted thereon is accomplished by longitudinal movement of the elongated rod 112, the slide plate 82 is transferred from the first track section 88 to the second track section 90, and then to the position shown in dotted lines in FIG. 1. In this position the platform 78 and the basket 86 located thereon are positioned within the heating chamber 42 and are disposed in the required location for the beginning of the heat treating cycle.

After completion of the heat treating cycle, the support member 77 is retracted to the original position thereof by movement of the elongated rod 112 in a rearward direction as controlled by the operation of the remote control device as previously described. Upon withdrawal of the support member 77 and the work basket 86 thereon to the original position thereof, it is necessary that the articles or work pieces that have been heat treated be immediately transferred to a quenching zone for the quick quenching thereof. Quick quenching of the work pieces is one of the novel features of the invention and is necessary in order to protect the surfaces of the Work pieces that have been heat treated and while these work pieces are still exposed to the vacuum within the housing 12. Rapid quenching will thus act to prevent oxidation or decarburization of the surfaces of the work pieces that have been heat treated and will cause an extremely clean and bright surface to be obtained.

As previously described the ring cage assembly 96 is designed to rotate the work support member 77 in an arcuate path for the purpose of transferring the heat treated articles to a quenching zone. The ring cage assembly 96 includes the spaced rings 92 and 94 that are interconnected by a plurality of spacer bars 156. As

. shown in FIG. the rings 92 and 94 are located in eccentric relation with respect to the cylindrical section 14 and are mounted for rotary movement on spaced support elements generally indicated at 158. The support elements 158 are joined to the interior surface of the cylindrical section 14 and define anti-friction means for promoting movement of the rings 92 and 94 thereon. Referring to FIG. 9, the support elements 158 are illustrated in detail and as shown each of these elements includes a plate 160 that is joined to the interior surface of the cylindrical section 14. Bolted to the plate 160 are angle sections 162 through which a mounting bolt 164 extends. Located on the mounting bolt is a graphite sleeve 166 that defines a bearing for a steel flanged roll 168 that is mounted thereon in coaxial relation. As shown in FIG. 9 a ring, indicated as the ring 92, is mounted on the steel flanged roll which provides for the free rotation thereof.

The rings 92 and 94 together with the spacer bars 156 define the ring cage assembly 96 which further include the first track section 88 that extends between the rings 92 and 94 and is joined thereto. In order to rotate the ring case assembly 96, one of the connecting bars 156 extends beyond the ring 92 and is joined to a lever 170. As shown in FIGS. 1 and 7 the lever 170 is formed with a hub 172 at the lower end thereof that is mounted on a shaft 174 that extends through the forward end wall 16 of the housing. The shaft 174 is carried by a bearing housing 176 that is mounted on the wall 16 and has a sprocket gear 178 mounted on the outermost end thereof. A chain 180 engages the sprocket 178 and further engages a lower sprocket gear 182 that is adapted to be rotated by a control member generally indicated at 184. Enclosing the bearing housing 176, sprocket gear 178 and the upper portion of the chain 180 is a housing 183 that is removably mounted on the jacket 22 and the housing 143 and communicates with the interior of the enclosure 33. The control member 184 includes an air cylinder 186 to which air lines 188 and 190 are joined. A piston rod 187 extends outwardly of the cylinder 186 and is operatively connected to the sprocket gear 182 for producing rotation thereof. It is seen that movement of the chain 180 may be conveniently controlled by the control member 184 for rotating the ring cage assembly 96 as re quired. It is seen that rotation of the ring cage assembly is available by movement of the pin 110 out of the notch 108 as the lever 170 is activated. The bar 106 is thus released from the rod 112 to permit rotation of the ring cage assembly.

In order to transfer the heat treated articles from the basket 86 to the quenching zone as previously indicated, a quench assembly is provided and is generally indicated at 192. The quench assembly includes a chute 194 that is cylindrical in construction and that includes an upper flange 196 that is bolted to a flange 198 that is formed as part of the cylindrical section 14. The chute 194 is thus fixed directly to the cylindrical section 14 of the furnace housing 12 and it is located directly below the ring cage assembly 96 and the first track section 88. Located within the cylindrical chute 194 are a plurality of downwardly extending spaced batfles 200. The baffles 200 are located in alternate spaced relation and are downwardly directed to allow passage of small parts therethrough, but are optically dense to prevent the diffusion of vapors that may be produced by the dropping of the heated articles into the quenching liquid that is contained in the quench assembly. To further prevent vaporization of the quench liquid and thereby prevent the vapors from entering into the interior of the furnace housing 12, cooling coils 202 are provided and extended around the chute 194, as illustrated in FIG. 1.

Located directly below the chute 194 is a quench tank 204 the uppermost end of which is provided with a flange 206 that is adapted to mate with a flange 208 joined to the lowermost end of the chute 194. The quench tank 204 is supported by rollers 208 that are mounted on brackets 210 that are, in turn, fixed to the outer surface of the lower end of the quench tank. The rollers 208 are adapted to be received on tracks 212 and are designed to provide for removal of the quench tank 204 from the assembled position thereof shown in FIG. 1.

The quench tank 204 is not physically joined to the lower end of the directing chute 194 but is lifted vertically so that the flanges 206 and 208 are placed in mating relation. Thereafter the vacuum created in the furnace housing which communicates directly with the interior of the directing chute 194 and the quench tank 204 provides for effectively sealing the flange 206 and 208. In order to lift the quench tank 204 to the sealing position thereof, spaced trunnions 214 are provided and are joined to opposite sides of the quench tank 204. As shown in FIGS. 4 and 5, a pivot bar 216 is mounted on a pivot post 218 and engages a trunnion 214 at one end thereof. Engaging the other end of the pivot bar 216 is an air operated rod 220 that extends into the cylinder 222. Control of the air into the cylinder 222 that is mounted on the horizontal support 32 causes the pivot bar 216 to be pivoted to the full line position as shown in FIG. 4. This raises the quench tank 204 from the dotted line position illustrated in FIG. 4 to the full line position thereof. The quench tank is thus lifted from engagement with the tracks 212 and is retained in sealing relation with the chute 194 during the heating and quenching cycles.

Contained within the quench tank 204 is a quenching medium such as oil that is maintained under proper temperature conditions to effectively quench the heated articles that are directed thereto through the directing chute 194 as the ring case assembly 96 is rotated to dump the articles from the basket 86. After a sufiicient time has elapsed for proper quenching of the articles that are dumped into the quench tank 204, the vacuum within the housing 12 is relieved and the quench tank 204 is dropped to the lower position for engagement with the tracks 212. The quench tank 204 is then rolled out of the position shown in full lines in FIG. 5 to the position illustrated in dotted lines in FIG. 5. A quench basket 224 located within the quench tank 204 and into which the articles have been directed is then removed with the articles therein from the quench tank for eventual removal of the articles for further handling. It is seen that the basket 224 is constructed of a wire mesh material that provides for free circulation of the quenching liquid therethrough and thus further providing for effective quenching of the articles that are deposited therein.

It has been found that if the quenching liquid can be effectively purified, the quenching cycle can be reduced and further contamination of the articles introduced into the quenching liquid can also be reduced with a resulting brighter surface on the treated articles. In order to purify the quenching liquid, circulation thereof is produced so as to expose all of the quenching liquid to the vacuum that is present in the furnace housing and the chute 194 and in that portion of the quench tank 204 that is not occupied by the quench liquid. The quenching oil is not only purified as all portions thereof are exposed to the high vacuum but circulation of the oil speeds the heat transfer cycle with a minimum time lapse for effectively cooling the articles that have been introduced into the quench tank. Circulation of the quenching oil within the quench tank is provided by locating an impeller 226 therein that is interconnected to a motor 228 through a pulley 230, belt 232 and a pulley 234. It is seen that the impeller may be continuously operated by the motor 228 independently, of the remote control device and will effectively purify the oil contained in the quench tank.

Referring now to FIG. 5, an alternate form of bafile construction is illustrated which includes a plurality of copper strips 236 that are held in position at the upper end thereof and that are adapted to be separated for allowing passage of the articles therethrough when they are directed into the chute 194 for passage into the quench tank 204 and the quenching medium therein. As further seen in FIG. the cooling coils 202 extend over a portion of the quench tank 204 and thus act to prevent vaporization of the quenching oil after introduction of the heated articles into the quench tank. As previously mentioned the baflies 200 or 236 are provided for preventing any oil that has vaporized from discharging from the chute 194 into the interior of the housing 12.

Operation The work to be heat treated is placed in the basket 86 which is then inserted into the open door 73 of the housing 12 and placed in interlocking position on the platform 78 of the support member 77. The control device 145 is then operated to move the elongated rod 112 in a longitudinal direction and toward the heating chamber 42. Through the interconnection of the connecting bar 106, the slide plate 82 and the support member 77 mounted thereon is moved on the first track section 88 to the second track section 90 and to the position illustrated in dotted lines in FIG. 1. In this position, the support member and the work load thereon are located within the heating chamber 42 and the heating chamber 42 is substantially sealed by the shields 102 and 104. Either before or after movement of the work load to the heating chamber, the interior of the housing 12 is evacuated to a predetermined vacuum by a vacuum pump that communicates with the interior of the housing 12 through the port 76. After the articles located in the basket 86 have been heat treated for a predetermined period of time, the control device 145 automatically operates to retract the support member 77 on which the basket 86 is located toward the position shown in full lines in FIG. 1. As soon as the support member 77 reaches the position that locates it between the rings 92 and 94 within the ring cage assembly 96, the slide plate 82 is disposed in the first track section 88 and this track section together with the ring cage assembly is now effectively moved through an arcuate path upon operation of the control device 184. The control device rotates the ring cage assembly 96 through an angle of approximately 180 which movement locates the basket 86 in position for dumping of the heat treated articles therefrom into the quench chute 194. The articles fall through the baffies 200 and into the quench liquid located in the quench tank 204. It is understood that prior to evacuating the housing 12 the quench tank 204 had been moved into positive engagement with the directing chute 194 by pivotal movement of the pivot bar 216 for locating the flange 206 in engagement with the flange 208.

The oil located within the quench tank 204 effectively removes the heat from the articles dumped therein and within an allowable time to obtain proper hardness and other required physical characteristics of the metals and alloys from which the articles are formed. vaporization of the quench liquid is substantially prevented by means of the cooling coils 202 that surround the chute 194 and the upper portion of the quench tank 204. If any of the oil is vaporized by a reduction in pressure of the atmosphere over the surface of the oil, this vaporized oil is prevented from entering into the interior of the housing 12 by means of the baffles 200.

The transfer of the heat treated articles from the interior of the heating chamber 42 to the quench tank 204 requires approximately two seconds, and thus it is seen that operation of the control device and control device 184 is timed such as to consume a minimum of time in moving the parts from heat to quench. By rapidly quenching in the manner as illustrated and described, the surfaces of the articles being heat treated are effectively protected. Protection is further insured by heat treating the articles under vacuum and transferring the articles to the quench tank without removing them from the vacuum chamber. This technique of heating under vacuum and rapidly quenching prevents contamination occurring on the surfaces of the articles and further provides the articles with an unusually bright surface.

While there is shown and described herein certain specific structure embodying the invention, it will be manifested to one skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept, and that the same is not limited to the particular forms herein shown and described, except insofar as indicated by the scope of the appended claims.

What is claimed is:

1. In a vacuum furnace, a furnace housing in which a predetermined vacuum is maintained during the heating cycle of the furnace, a heating chamber located in said housing, means for supplying the required temperature in said heating chamber, a support member located in said housing and being adapted to receive a work load thereon, means for mounting said support member in said housing, means for moving said support member with the work load thereon in a longitudinal direction from a first station into said heating chamber and for withdrawing said support member and Work load thereon from said heating chamber for return to said first station, a quench tank communicating with said housing maintained at a predetermined vacuum and means for moving said support member at said first station in a arcuate path after the removal thereof from said heating station to dump said work load into said quench tank for quick quenching of the work load therein.

2. 'In a vacuum furnace for heat treating metallic articles, a housing in which a predetermined vacuum is maintained during the heating cycle of the furnace, a heating chamber located in said housing, means for supplying the required temperature in said heating chamber, a movable support member located in said housing and being adapted to receive a load of metallic articles to be heat treated thereon, means for conveying said support member and load thereon in a longitudinal direction into said heating chamber and for withdrawing said support member and load thereon from said heating chamber after the heating cycle, and means for moving said support member and load thereon in an arcuate path immediately after withdrawal thereof from said heating chamber, wherein the articles that have been heat treated are dumped from said support member into a quench tank for the quick quenching thereof, said quench tank being maintained at a predetermined vacuum.

3. In a vacuum furnace for heat treating metallic articles, a housing which is maintained under a predetermined vacuum during the heating cycle of said furnace, a heating chamber located in said housing, means for supplying the required temperature in said heating chamher, a support member located in said housing on which the articles to be heat treated are carried, a track assembly mounted in said housing and including a longitudinally extending movable first track section and a longitudinally extending fixed second track section disconnected from said first track section and located beneath said heating chamber, a ring cage assembly secured to said first track section and being mounted for rotary movement therewith, means for quenching the articles after the heat treating thereof, said quenching means communicating with said housing and being located below said ring cage assembly and being maintained at a predetermined vacuum, a slide member on which said support member is mounted, being receivable in said first track section and being movable in a longitudinal direction therein but being rotatable therewith and said ring cage assembly, means interconnected to said slide member for moving said slide member and support member fixed thereto off said first track section and into said second track section, wherein said support member and articles are moved into said heating chamber, said moving means being operative to return said slide member and support member from said second track section onto said first track section after the heat treating cycle, and means for rotating said cage assembly after return of said support member and articles thereon to said first track section wherein the articles that have been heat treated are transferred into the quenching means for the quick quenching thereof.

4. In a vacuum furnace for heat treating metallic articles, a housing which is maintained at a predetermined vacuum having a first station for loading and unloading said articles, and a second station at which said articles are heated in a heating zone, means for supporting said articles in said housing, means for moving said supporting means in a longitudinal direction from said first station to said second station and for returning said articles in a longitudinal direction to said first station after a predetermined heating cycle, means for moving said sup porting means in an arcuate path to transfer said heat treated articles therefrom, and means located below said first station for receiving said heat treated articles therein for the quick quenching thereof, said receiving means communicating with said housing and being maintained at substantially the same vacuum therein.

5. In a vacuum furnace as set forth in claim 4, means for guiding said supporting means including a longitudinal first track section located at said first station and movable in an arcuate path with arcuate moving means, and a longitudinal second track section disconnected from said first track section and extending beneath said second station.

6. In a vacuum furnace as set forth in claim 5, said means for moving said supporting means in a longitudinal direction including a slide plate that is received within said track sections and having a platform interconnected thereto on which a load carrying member is mounted, a Work transfer rod interconnected to said slide plate, and means for controlling movement of said work transfer rod for moving said slide plate and load platform interconnected thereto in the longitudinal direction thereof.

7. In a vacuum furnace as set forth in claim 5, said arcuate moving means including spaced rings that are interconnected by spacer elements, said first track section being joined to said spaced rings and movable in an arcuate path therewith, and means interconnected to said spaced rings for rotating said rings after said supporting means has been moved to said first station following the heating cycle, whereby rotation of said rings carries the first track section joined thereto to a position for transferring the heat treated articles to said quenching means.

8. In a vacuum furnace as set forth in claim 4, said second station being defined by a heating chamber in which heating elements are provided for heating said heating chamber to a predetermined temperature, said heating chamber including walls having openings for receiving said supporting means therein, and shields mounted on said supporting means and movable therewith into contact with said walls for enclosing said openings during the heating cycle, of the articles being heat treated in said heating chamber.

9. In a vacuum furnace as set forth in claim 4, said quenching means including a cylindrical guide member fixed to said housing and communicating with the interior thereof and a quench tank removably joined to said guide member and containing a quench liquid therein, said arcuate moving means dumping said heat treated articles through said guide member and into the quench liquid in said quench tank for the quick quenching thereof.

10. In a vacuum furnace as set forth in claim 9, a plurality of downwardly directed bafies located in said guide member for protecting the interior of said housing during the quenching operation.

11. In a vacuum furnace as set forth in claim 9, a removable basket located in said quench tank into which said heat treated articles are directed, said basket being removable from said quench tank after the quenching operation for further handling of the articles located therein.

12. In a vacuum furnace as set forth in claim 9, means located in said quench tank for circulating the quench liquid therein, wherein the quench liquid is exposed to the vacuum in said housing and is purified for expediting the quenching operation.

13. In a method of heat treating metallic articles in a vacuum furnace comprising the steps of placing said articles on a load platform within the housing of said furnace, evacuating said housing to a predetermined vacuum pressure, moving said load platform and articles thereon in a longitudinal direction into a heat chamber for the heat treatment of said articles for a predetermined period of time, withdrawing said load platform and articles thereon in a longitudinal direction after completion of the heat treatment of said articles to the original position thereof, rotating said platform for dumping said articles from said platform into a quenching liquid that is contained within a tank that communicates with said housing and that is maintained at a predetermined vacuum wherein the quenching operation of said articles is carried out under vacuum, and removing said tank from communication with said housing for withdrawal of said articles therefrom for further handling.

14. A bafiie construction for use in combination with a quench tank having a quench liquid contained therein that is adapted to receive heat treated articles therein for the quenching thereof, a plurality of metallic sheets of a material having a high thermal conductivity, said sheets being arranged in segments and being supported at the upper end thereof, the lower ends of said sheets being unsupported and being movable when an article is directed therebetween for passage into said tank, said sheets being optically dense for preventing diffusion of vaporized quenching liquid that results when the heat treated articles are deposited into the quenching liquid for the quenching thereof.

15. In a vacuum furnace, a furnace housing in which a predetermined vacuum is maintained during the heating cycle of the furnace, a heating chamber located in said housing, means for supplying the required temperature in said heating chamber, a support member located in said housing for receiving a Work load thereon, a quench zone maintained at a predetermined vacuum and communicating with said housing, a quench liquid disposed in said quench zone and being located substantially below the level of the heating chamber, a portion of said quench zone being located above the level of said quench liquid and directly communicating with said housing, means for moving said support member with the work load therein in a longitudinal direction from a loading position into said heating chamber and for removing said support member and work load thereon from said heating chamber after the heating cycle, means for directing said heat treated articles into said quench zone for quenching the articles in said quench liquid, and cooling means surrounding the portion of said quench zone above the level of said quench liquid for condensing vapors of the quench liquid that occur during the quenching operation, wherein the vapors from the quench liquid are prevented from entering into the interior of the furnace.

16. In a vacuum furnaceas set forth in claim 15, an impeller located in said quench zone and submerged in said quench liquid, said impeller being operable to produce continuous circulation of said quench liquid during the quenching operation for purifying said quench liquid and for further aiding in cooling the articles being quenched, wherein vaporization of said quench liquid is effectively reduced. 1 f

17. :In a vacuum furnace as set forth in claim 15, said directing means moving said heat treated articles into said quench zone in a direction that is substantially transverse to the direction in which the articles are moved out of'the heating chamber.

References Cited UNITED STATES PATENTS 7/ 1927 Callaghan 266-4 OTHER REFERENCES A High-Temperature Vacuum Quench Furnace, Atomics Int. Div. of N. American Aviation, NAA SR-2312, September 1958, pp. 3-8, 10, 12 and 13.

10 CHARLES N. LovELL, Primary Examiner.

US. Cl. X.R. 

